The disclosure relates to a motor drive control apparatus, a motor drive control method and a program of the same.
Traditionally, in a drive motor or generator disposed as a electric machine, a rotor is rotatably disposed which has a magnetic pole pair formed of north- and south-pole permanent magnets, and a stator is disposed in the outward radial direction from the rotor, the stator having coils of U-phase, V-phase, and W-phase.
A motor drive apparatus is disposed which drives the drive motor or generator to generate drive motor torque (torque of the drive motor) or generator torque (torque of the generator), and a motor drive control apparatus is disposed in order to control the motor drive apparatus. The motor drive control apparatus has a drive motor control unit which drives the drive motor and a generator control unit which drives the generator as electric machine control units. The drive motor or generator control unit sends pulse width modulation (PWM) signals of U-phase, V-phase, and W-phase generated in the electric machine control unit to an inverter, and feeds phase current generated in the inverter, that is, the currents in U-phase, V-phase, and W-phase to the individual stator coils to conduct PWM control for generating the drive motor torque and the generator torque.
The PWM control has asynchronous PWM control that generates asynchronous PWM signals in a sine wave PWM pattern, and synchronous PWM control that generates synchronous PWM signals in a pulse pattern formed of odd-numbered pulses, that is, a one-pulse pattern, a three-pulse pattern, a five-pulse pattern, a seven-pulse pattern, and so on. A motor drive control apparatus is provided which can switch between the asynchronous PWM control and the synchronous PWM control. In the motor drive control apparatus, the asynchronous PWM control is conducted in a medium-speed rotation area or low-speed rotation area and the synchronous PWM control is conducted in a high-speed rotation area (for example, see JP03-395815).
Next, a drive motor control unit, such as found in JP03-395815, that can conduct the synchronous PWM control will be described.
FIG. 2 is a block diagram illustrating the essential part of a traditional drive motor control unit. In the drawing, 22 denotes a phase counter. The phase counter 22 receives an A-phase signal SG-A and a B-phase signal SG-B that are sent as magnetic pole position signals from a magnetic pole position sensor (not shown) and computes the magnetic pole position θ based on the signals SG-A, SG-B.
A voltage command value computation processing part 48 has a current control part 61 and a voltage command converting part 63. The current control part 61 reads a d-axis current command value id* and a q-axis current command value iq*, and computes a d-axis voltage command value vd* and a q-axis voltage command value vq* based on the d-axis current command value id* and the q-axis current command value iq*. The voltage command converting part 63 reads the d-axis voltage command value vd* and the q-axis voltage command value vq*, and computes the voltage amplitude |v| and the voltage phase angle γ on the d-q coordinates based on the d-axis voltage command value vd* and the q-axis voltage command value vq*.
A PWM generator 50 has an adder 65, a percent modulation computing part 71, a pattern generating part 72, a magnitude comparator 74 as a comparison processing module, and an on-off output part 75. It reads the magnetic pole position θ, the voltage amplitude |v|, and the voltage phase angle γ, and generates pulse width modulation signals Mu, Mv, Mw in a one-pulse pattern, for example, the signals are the synchronous PWM signals of U-phase, V-phase, and W-phase.
Therefore, the adder 65 receives the magnetic pole position θ and the voltage phase angle γ, adds the voltage phase angle γ to the magnetic pole position θ, and computes the voltage phase angle β on the fixed coordinates. The percent modulation computing part 71 reads the DC voltage Vdc of an inverter as well as reads the voltage amplitude |v| from the voltage command converting part 63, and computes the percent modulation ρ indicative of the voltage utilization rate based on the voltage amplitude |v| and a value 0.78×Vdc that represents acceptable voltage:ρ=|v|/(0.78×Vdc).
The pattern generating part 72 reads the percent modulation ρ, generates a one-pulse pattern in response to the percent modulation ρ, and computes the switching voltage phase angle βj (j=u, v, w) indicative of the switching angle in the individual phases on the fixed coordinates and the output level va in order to define the one-pulse pattern. The magnitude comparator 74 reads the voltage phase angle β and the switching voltage phase angle βj, and generates the on-off switching signal ε at the timing when the voltage phase angle β exceeds the switching voltage phase angle βj. When the output level va and the on-off switching signal ε are inputted, the on-off output part 75 generates the pulse width modulation signals Mu, Mv, Mw, that are the synchronous PWM signals in the individual phases, based on the output level va and the on-off switching signal ε. The pulse width modulation signals Mu, Mv, Mw have the output level va as amplitude, and are activated when the on-off switching signal ε is turned on and deactivated when it is turned off.